Heating apparatus

ABSTRACT

A HEATING APPARATUS INCLUDING ENCLOSURE MEANS DEFINING A COMBUSTION CHAMBER, MEANS FOR DISTRIBUTING HEATED AIR FROM SAID COMBUSTION CHAMBER, AND A BURNER UNIT DISPOSED IN SAID COMBUSTION CHAMBER COMPRISING A FIRST VENTURI HAVING AN INLET PORT AND AN OUTLET PORT PARTIALLY DEFINING A COMBUSTION ZONE, THE FIRST VENTURI HAVING AT LEAST ONE PRIMARY AIR INTAKE PORT, A FIRST FUEL SUPPLY LINE COMMUNICATING WITH THE INLET PORT OF THE FIRST VENTURI, A SECOND VENTURI MOUNTED ON THE FIRST VENTURI HAVING AN INLET PORT AND AT LEAST ONE OUTLET PORT COMMUNICATING WITH THE COMBUSTION ZONE, THE SECOND VENTURI HAVING AT LEAST ONE PRIMARY AIR INTAKE PORT DIRECTLY COMMUNICATING WITH THE INTERIOR OF THE FIRST VENTURI, A SECOND FUEL SUPPLY LINE COMMUNICATING WITH THE INLET PORT OF THE SECOND VENTURI, AND THE FIRST VENTURI HAVING A LARGER CAPACITY THAN THE SECOND VENTURI WHEREBY THE SECOND VENTURI MAY BE OPERATED TO PROVIDE A LOW FIRING RATE AND THE FIRST VENTURI MAY BE OPERATED WITH OR WITHOUT THE SECOND VENTURI TO PROVIDE HIGHER FIRING RATES.

Feb. 9, 1971 w. F. JACK-SON ETAL HEATING APPARATUS Filed Dec. 20, 1968 `2 Sheets-Sheet 1 HIIIIII Mmmm INVENTORS F. IAcKsoN y WLTEP.

Taw.

Feb. 9, 1971 w. F. JACKSON ETAL 3,561,901

HEATING APPARATUS 2 Sheets-Sheet 2 Filed Dec. 20, 1968 INVENTORS WALT-etz. F. JACKSON JAMES F. \N\se= BY YY) as mf'wundlu 6mm ATTORNEYS United States Patent O 3,561,901 HEATING APPARATUS Walter F. Jackson and James F. Wise, Clinton, N.C., assignors to Vann Industries, Incorporated, Clinton, N.C., a corporation of West Virginia Filed Dec. 20, 1968, Ser. No. 785,483 Int. Cl. F23m 9/ 00 U.S. Cl. 431-284 16 Claims ABSTRACT OF THE DISCLOSURE A heating apparatus including enclosure means defining a combustion chamber, means for distributing heated air from said combustion chamber, and a burner unit disposed in said combustion chamber comprising a first venturi having an inlet port and an outlet port partially defining a combustion zone, the first venturi having at least one primary air intake port, a first fuel supply line communicating with the inlet port of the first venturi, a second venturi mounted on the first venturi having an inlet port and at least one outlet port communicating with the combustion zone, the second venturi having at least one primary air intake port directly com? municating with the interior of the first venturi, a second fuel supply line communicating with the inlet port of the second venturi, and the first venturi having a larger capacity than the second venturi whereby the second venturi may be operated to provide a low ring rate and the first venturi may be operated with or without the second venturi to provide higher firing rates.

This invention relates to a novel heating apparatus and more particularly to a heating apparatus adapted for curing tobacco. This invention further contemplates a novel burner unit for a heating apparatus operable to provide different firing rates.

In the curing of tobacco, the primed tobacco leaves commonly are cured by placing them in tobacco barns and subjecting the tobacco leaves to heated air at predetermined temperatures and for predetermined periods of time. Initially, the tobacco leaves are subjected to heated air in the temperature range of 90 to 100 F. for a period of about 30 to 6() hours. This first stage of the curing cycle causes the leaves to undergo a physiological transformation, during which the starch and protein molecules of the leaves are chemically converted, and the chlorophyll in the leaves is oxidized, causing the leaves to turn yellow. This first stage commonly is referred to as the yellowing stage. Upon completion of the yellowing stage the temperature of the heated air is increased to the range of 130 to 135 F. and held in such range for a period of approximately to 30 hours. During this second stage of the curing cycle, the physiological transformation or yellowing of the tobacco leaves is halted and the leaves are dehydrated.

In the prior art there are numerous types of heating apparatus for curing primed tobacco leaves. It has been found, however, that most of' the heating apparatus in the prior art is not entirely satisfactory in performance and safe in operation.

Accordingly, it is the principal object of this invention to provide a novel heating apparatus.

Another object of this invention is to provide a novel heating apparatus for curing tobacco leaves.

A further object of this invention is to provide an improved heating apparatus for curing tobacco leaves, which is adapted to pro-vide different heat outputs.

A still further object of the present invention is to provide an improved heating apparatus for curing tobacco leaves, which is adapted to provide a relatively low heat p ICC output suitable for the yellowing stage in the tobacco curing cycle and a relatively high heat output suitable for the dehydration stage of the tobacco curing cycle.

Another object of the present invention is to provide a novel heating apparatus particularly adapted for curing tobacco leaves, which is comparatively simple in construction, elfective in performance and safe in operation.

A further object of the present invention is to provide a novel burner unit.

A still further object of the present invention is to provide a novel burner unit for a heating apparatus suitable for curing tobacco leaves.

Another object of the present invention is to provide a novel burner unit having high and low firing rates.

A further object of the present invention is to provide a novel burner unit, which is simple in construction, and eiiicient and safe in operation.

Other objects and advantages of the present invention will become more apparent to those persons skilled in the art to which the present invention pertains, from the following description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of an embodiment of the invention;

FIG. 2 is an enlarged cross-sectional view taken along line 2 2 in FIG. 1;

FIG. 3 is an enlarged vertical cross-sectional view of a portion of the burner unit utilized in the embodiment shown in FIGS. 1 and 2, illustrating the burner unit operating at a low firing rate; and

FIG. 4 is a vertical cross-sectional View of the burner unit included in the heating apparatus shown in FIGS. 1 and 2, illustrating the burner unit operating at a higher firing rate.

Briey described, the present invention relates to a heating apparatus generally including an enclosure means defining a combustion chamber, means for distributing heated air from the combustion chamber, and a burner unit disposed in said combustion chamber comprising a first venturi including a horizontal section having an inlet port and at least one primary air intake opening, and a vertical section having an outlet port partially defining a combustion zone, a first fuel supply line communicating with the inlet port of the first venturi, a second venturi mounted in the vertical section of the first venturi having an inlet port and at least one outlet port communicating With the combustion zone, the second venturi having at least one primary air intake port directly communicating with the interior of the first venturi, a second fuel supply line communicating with the inlet port of the second venturi, and the first venturi having a larger capacity than the second venturi whereby the second venturi may be operated to provide a low firing rate and correspondingly produce a predetermined low heat output, and the first venturi may be operated with or without the second venturi to provide higher firing rates and correspondingly to produce predetermined higher heat outputs Referring to the drawings, there is illustrated an embodiment of the invention. The embodiment generally includes an enclosure unit 10, defining a combustion chamber 11, a burner unit 12 mounted below and partially within the combustion chamber 11, and a heat distribution system 13 vfor distributing the heated air emanating from the combustion chamber 11. The enclosure unit 10 consists of a circular wall membr 14 which is supported on a plurality of leg members 15 so that the bottom edge 16 thereof is disposed in spaced relation to the floor surface 17, and a cover mem-ber 18 closing the upper end thereof. Mounted on the cover member 18 is a cover or shield member 19. The upper end of the wall member 14 is provided with a plurality of outlet ports about the circumference thereof, which are provided with tubular mounting ducts 21. Each of the mounting ducts is disposed substantially radially relative to the vertical axis of the circular wall member 14.

The heat distribution system 13 comprises a plurality 0f elongated tubular duct members 22 mounted on the mounting duct members 21 and extending radially to points adjacent the side Walls of the housing structure in which the heating apparatus is located. Each of the duct members 22 is provided With a baiile member 23 mounted on the end thereof. Each duct member 22 and its associate baffle member 23 is supported at its outer end by a leg member 24. It will be appreciated that the lengths of the tubular duct members 22 can be varied to provide the desired distribution of heated air emanating `from the combustion chamber 11.

As best illustrated in FIG. 2, the burner unit 12 generally includes a rst venturi 25 having a horizontal section 26 and a vertical section 27, and a vertically disposed venturi 28 mounted in the vertical section 27 of venturi 25. The venturi 25 is supported on a pair of [brackets 29 and 30 suspended from the circular wall 14 of the enclosure unit, so that the horizontal section 26 of the venturi 25 will be disposed below the lower edge of the circular Wall 14 and radially relative to such wall, and the vertical section 27 of venturi 25 will be disposed substantially axially relative to the circular Wall 14 and will extend into the lower end of the combustion chamber 11.

The venturi section 26 includes an oriiice 31 having an inlet port communicating with a fuel supply line 32 and primary air intake ports 33 disposed adjacent the oriiice 31. The venturi section 27 communicates directly with the venturi section 26, and is provided with an outlet opening 34 partially defining and communicating with a combustion zone 35. In normal operation, fuel and primary air introduced into venturi -25 throughoriiice 31 and primary air intake ports 33 are mixed and ejected through outlet port 34 into combustion zone 35, where the `fuel-air mixture combines with secondary air and is ignited.

The venturi 28 is disposed coaxially relative to the venturi section 27, and is mounted in a bottom wall portion thereof. The venturi 28 is provided With an orifice 36 having an inlet port communicating with a fuel supply line 37 connected to the main fuel supply line 32, having a manually operated shut-off valve 38. The lower end of the venturi 28 also is provided with a plurality of primary air intake ports 39 which communicate directly with the interior of the venturi 25. The venturi 28 further is provided with an adapter 40 at the upper end thereof. The adapter 40 is substantially cylindrical in configuration and is provided with a plurality of radial burning ports 41 communicating with the combustion zone 35. Mounted on the upper end of the Venturi 28 is a baille member 42 having a convex bottom surface 43 disposed adjacent the combustion zone 35. In normal operation, fuel and air introduced into the venturi 28 through oriiice 36 and primary air intake ports 39' will mix as they traverse the length of the venturi 28 and will be ejected through burner ports 41 where the air-fuel mixture combines with secondary air and is ignited. The flames emanating from the combustion zone will be diverted radially by the conically configured bottom surface 43 of the baiile 42 and heat the air in the combustion chamber 11.

The venturi section 27 also is provided with a bracket 44 on which there is mounted a pilot burner 45, a thermocouple 46, and a termoelectric generator 47. The pilot burner 45 is provided with a diverter baffle 48 which is adapted to divert the flame of the pilot burner toward the combustion zone 35 to ignite fuel-air mixtures emanating either from outlet port 34 of venturi 25, or burner ports 41 of venturi 28. The pilot burner 45 is provided 4 with a fuel supply line 49 which is connected to a pilot safety valve 50 mounted in the main fuel supply line 32. The thermocouple 46 is disposed in heat transfer relation to the llame of the pilot burner 45 and is electrically connected to the pilot safety valve 50 by means of an electrical line 51. The pilot safety valve 50 is of the type that is normally in the closed position which prevents the flow of yfuel through the main supply line 32 and the pilot burner fuel supply line 49. The valve 50 is opened by depressing a reset plunger 52 and normally will remain open only when the plunger 52 is depressed, unless the pilot burner is lit and the thermocouple 46 is heated by the flame of the pilot burner to generate an electrical current in line 51 to retain the valve 50 in the open position.

The main fuel supply line 32 also is provided with a manual shut-olf valve 53 and a thermostatically controlled valve 54. The thermostatically controlled valve 54 is connected to a thermostat 55 by means of an electrical lead line 56 and is operable responsive to the thermostat. The valve 54 also is connected to the thermoelectric generator 47 disposed in heat transfer relation with the iiame of the pilot burner 45, by means of an electrical lead line 57. In addition to being operative responsive to the thermostat 55, the valve 54 is operable responsive to the operation of the thermoelectric generator 49, whereby the valve 54 will remain open only so long as the pilot burner 45 is lit and heat is being generated to the thermoelectric generator 47. It will be understood that the heat generated by the pilot burner will generate a current in the thermoelectric generator 47 sufficient to actuate the valve 54 into the open position.

k When the heating apparatus as described is in the nonoperating condition, the pilot safety valve 50, the thermostatically controlled valve 54, the pilot burner supply line shut-off valve 38, and the main fuel supply shut-oif valve 53 are all in the closed positions. When it is desired to operate the heating apparatus to provide a comparatively low heat output, such as is required during the yellowing stage in the curing cycle of tobacco leaves, the thermostat 55 is set at lthe appropriate temperature and the burner unit is then set to be lit oif. To light oif the burner unit, the plunger 52 of the pilot safety valve 50y is depressed so that fuel will ilow through fuel supply line 49 to the pilot burner 45. The pilot burner is then lit off while the plunger 52 is maintained in the depressed position. After the pilot burner has been burning for a short period of time, sufficient heat will be generated to activate the thermocouple 46 which generates a voltage suiiicient to retain the plunger 52 in the depressed position and correspondingly, maintain the valve 50 in the open position. The temperature differential in the thermostat 55, and the current generated by the thermoelectric generator 47 Will cause the control valve 54 to open. The venturi 28 then can be operated by opening the shut-olf valve 38. As soon as this is accomplished, fuel Will iioW through fuel supply line 37 and be introduced through the oriiice 36 into venturi 28 Where it will be mixed with primary air introduced through inlet ports 39. As the fuel-air mixture is ejected through burner ports 41 into combustion Zone 35, it will be ignited by the pilot burner ilame. The flame emanating from the combustion zone 35 will engage the convex surface 43 of baffle 42 and be diverted radially to heat the air in the combustion chamber 11, as illustrated in FIG. 3. The burner unit will then continue to operate at a low iiring rate as longr as the valve 54 remains open. As previously mentioned, the valve 54 will remain open unless the pilot burner becomes extinguished or the temperature of the area being heated exceeds the temperature setting of the thermostat 55.

When it is desired to operate the burner -unit at a higher firing rate to produce a higher heat output as desired during the dehydration stage in the curing cycle of tobacco, the temperature setting of the thermostat 55 is advanced to a higher reading and the valve 53 is opened to supply fuel to the venturi 25. Fuel introduced into the venturi through orifice 31 and primary air introduced through intake ports 33 mixes as it traverses through venturi 25, and is ejected through outlet port 34 into combustion zone 35 where it mixes further with secondary air and is ignited by the flame of pilot burner 45. The liame emanating from the lventuri 25 also engages the concave surface 43 of bafile 42 and is diverted radially to heat the air in the combustion chamber 11, as illustrated in FIG. 4.

It will be appreciated that the venturi 28 can be operated alone to provide a low firing rate, the venturi 2S can be operated to provide an intermediate firing rate, or the venturi 25 and 28 can be operated simultaneously to provide a high firing rate. This can be accomplished simply by setting the thermostat to the appropriate temperature reading and adjusting the shut-off valves 38 and 53. With the appropriate thermostat settings, the burner can be operated at a low firing rate by opening the valve 88 and closing the valve 53, at an intermediate firing rate by closing the valve 38 and opening the valve 53, and at a high firing rate by opening both valves 38 and S3.

The thermocouple 46 and the thermoelectric generator 47 provide a maximum safe operation of the heating apparatus, in that upon extinguishment of the pilot burner, voltages will be generated by the thermocuple 46 and the thermoelectric generator 47 to close safety pilot valve 50 and control valve 54.

The heated air in the combustion chamber 11 will flow through the openings 20 in circular wall 14 of the enclosure unit, and through the tubular duct members 22 to be distributed to various parts of the housing structure being heated. The temperature of the housing structure bring heated is controlled by the thermostat 55. Cold air in the housing structure will descend and be drawn through the lower open end of the enclosure unit 10 to be heated by the burner unit 12 and recirculated through the distribution system 13.

Having thus described an embodiment of our invention, we claim:

1. A heating apparatus comprising enclosure means defining a combustion chamber, means for distributing heated air from said combustion chamber, and a burner unit disposed in said combustion chamber comprising a first venturi having an inlet port and an outlet port at least partially defining a combustion zone, said first venturi having at least one primary air intake port, a first fuel supply line communicating with the inlet port of said first venturi, a second venturi mounted on said first venturi having an inlet port and at least one outlet port communicating with said combustion zone, said second venturi having at least one primary air intake port directly communicating with the interior of said first venturi, a second fuel supply line communicating with the inlet port of said second venturi, and said first venturi having a larger capacity than said second venturi whereby said second venturi may be operated to provide a lo-w firing rate and correspondingly produce a predetermined low heat output and said first venturi may be operated with or without said second venturi to provide higher firing rates and correspondingly to produce predetermined higher heat outputs.

2. A burner unit comprising a first venturi having an inlet port and an outlet port at least partially defining a combustion Zone, said first venturi having at least one primary air intake port, a first fuel supply line communicating with the inlet port of said first venturi, a second venturi mounted on said first venturi having an inlet port and at least one outlet port communicating with said combustion zone, said second venturi having at least one primary air intake port directly communicating with the interior of said first venturi, a second fuel supply line communicating with the inlet port of said second venturi, and said first venturi having a larger capacity than said second Venturi whereby said second venturi may be operated to provide a low firing rate and correspondingly to produce a predetermined low heat output and said first venturi may be operated with or |without said second venturi to provide higher firing rates and correspondingly to produce predetermined higher heat outputs.

3. A burner unit according to claim 2, including a baflie for spreading the fiame emanating from said first and second venturi during operation of the burner unit.

4. A burner unit according to claim 2, including a pilot burner disposed adjacent said combustion zone for igniting fuel-air mixtures emanating from the outlet ports of said venturi.

5. A burner unit according to claim 4, including a fuel supply line for said pilot burner, a safety valve in said fuel supply lines for venturi, a thermocouple disposed in heat transfer relation with said pilot burner, and said safety valve being operable responsive to the operation of said thermocouple.

6. A burner unit according to claim 2, including a thermostatically controlled valve disposed in said fuel supply lines for said venturi.

7. A burner unit according to claim 4, including a thermostatically controlled valve disposed in the fuel supply lines of said venturi and a thermoelectric generator disposed in heat transfer relation with said pilot burner operable to close said thermostatically controlled valve upon extinguishment of said pilot burner.

8. A burner unit according to claim 2, including a baffle for spreading the flame emanating from said first and second venturi during operation of the burner unit, a pilot burner disposed adjacent said combustion zone for igniting fuel-air mixtures emanating from the outlet ports of said Venturi, a fuel supply line for said pilot burner, a safety valve in said fuel supply lines for said venturi, a thermocouple disposed in heat transfer relation with said pilot burner operable to close said safety valve upon extinguishment of said pilot burner, and a thermostatically controlled valve disposed in said fuel supply lines for said venturi.

9. A heating apparatus comprising enclosure means defining a combustion chamber, means for distributing heated air from said combustion chamber, and a burner unit disposed in said combustion chamber comprising a first venturi including a horizontal section having an inlet port and at least one primary air intake port, and a vertical section having an outlet port at least partially defining a combustion zone, a first fuel supply line communicating with the inlet port of said first venturi, a second venturi vertically mounted in the vertical section of said first venturi having an inlet port and at least one outlet port communicating with said combustion zone, said second venturi having at least one primary air intake port directly cornmunicating with the interior of said first venturi, a second fuel supply line communicating with the inlet port of said second venturi, and said first venturi having a larger capacity than said second Venturi whereby said second venturi may be operated to provide a low firing rate and correspondingly produce a predetermined low heat output and said first venturi may be operated with or without said second venturi to provide higher firing rates and correspondingly to produce predetermined higher heat outputs.

10. A burner unit comprising a first venturi, including a horizontal section having an inlet port and at least one primary air intake port, and a vertical section having an outlet port at least partially defining a combustion zone, a first fuel supply line communicating with the inlet port of said yfirst venturi, a second venturi vertically mounted in the vertical section of said first venturi having an inlet port and at least one outlet port communicating with said combustion zone, said second venturi having at least one primary air intake port directly communicating with the interior of said first venturi, a second fuel supply line communicating with the inlet port of said second venturi, and said first venturi having a larger capacity than said 7 second venturi whereby said second venturi may be operated to provide a low firing rate and correspondingly to produce a predetermined low heat output and said rst venturi may be operated with or Without said second venturi to provide higher tiring rates and correspondingly to produce predetermined higher heat outputs.

11. A burner unit according to claim 10, including a baille for spreading the Iflame emanating from said rst and second venturi during operation of the burner unit.

12. A burner unit according to claim 10, including a pilot burner disposed adjacent said combustion zone for igniting fuel-air mixtures emanating from the outlet ports of said venturi.

13. A burner unit according to claim 12, including a fuel supply line for said pilot ourner, a san-.ty Vvalve 1n said fuel supply lines for said venturi and a thermocouple disposed in heat transfer relation With said pilot burner operable to close said safety valve upon extinguishment of said pilot burner.

14. A burner unit according to claim '10, including a thermostatically controlled valve disposed in said fuel supply lines for said venturi.

15. A burner unit according to claim 12, including a thermostatically controlled valve disposed in the fuel supply lines of said venturi and a thermoelectric generator disposed in heat transfer relation with said pilot burner operable to close said thermostatically controlled valve upon extinguishment of said pilot burner.

16. A burner unit according to claim 10, including a bale for spreading the flame emanating from said dirst and second venturi during operation of the burner unit, a pilot burner disposed adjacent said combustion zone for ignting fuelair mixtures emanating from the outlet ports of said venturi, a fuel supply line for said pilot burner, a safety valve disposed in the fuel supply lines of said first and second venturi, a thermocouple disposed in heat transfer relation with said pilot burner operative to close said safety valve upon eXtinguishment of said pilot burner, and a thermostatically controlled valve disposed in said fuel supply lines for said rst and second venturi.

References Cited UNITED STATES PATENTS EDWARD G. FAVORS, Primary Examiner U.S. C1. X.R. 263-19 

